The new Camp Nelson Bridge, just completed
on Lancaster Road, eight miles south of Nicholasville, across
the Kentucky River, has a location at once scenic and of historic
interest.

The name Camp Nelson was first applied during
the Civil War to a Union military encampment and system of fortifications
established on the hills just northeast of the bridge site.

The new bridge also replaces a picturesque
and extremely interesting old wooden bridge, which, erected in
1838 and still standing, though condemned for use, is a unique
monument to the past and to the men who built it; unique in that
it is probably the oldest wooden span still standing in the United
States, and also in its length of span and type of construction.
It was built for the state of Kentucky by Lewis V. Wernwag, a
native of Pennsylvania and eminent bridge builder of his time.
Its construction is said to have cost $30,000, including the
masonry abutments.

In its type of construction, the old wooden
bridge consists essentially of three timber arches, each arch
rib stiffened by timber trusses extending the full length of
the bridge. Each arch rib is made up of six timbers sized six
inches by 12 inches, arranged two horizontal and three vertical.
As each arch rib passed through stiffener trusses, the posts
and diagonals of the latter are neatly dipped to allow the arch
rib to pass through intact, all butt-joints of the arch rib members
being located at and concealed by the truss posts. The exceptional
workmanship, shown in joint fittings throughout the bridge, is
nothing short of marvelous and is tangible evidence of the extreme
care taken in its construction.

A 235-Foot Span

The three arch ribs have a clear span of 235
feet, setting on solid masonry abutments at each end, and are
held in vertical position by a timber top lateral truss system
extending full width of the bridge, attached to the tops of the
three stiffening trusses, which separate the two separate roadways
provided, each 12 feet in width.

The bottom lateral system consisted of one
inch square wrought iron tire-rods, arranged diagonally, crosswise
beneath the stiffener trusses. Many of these are now broken off
due to excessive settlement of bridge.

The entire bridge is roofed and sided over
as weather protection. For the reader who may be interested,
a more detailed description of the construction details of this
old wood bridge is to be found in Engineering News Record, issue
of February 9, 1928.

Built at a time when exact methods of bridge
stress analysis were unknown, we can only pause in wonder and
admiration at this old bridge, which would be a credit to a modern
designer in its type, and which with its 88 years of continuous
service presents a record unparalleled in American bridge annals.
Interesting, indeed, would be a chronology of the nation's historical
events which this old bridge has outlived, extending back to
the days when Kentucky was still in the pioneer stage of its
development, when vast unsettled domains lay west of the Mississippi,
and Andrew Jackson was president. Could it but speak, it could
tell us of General Scott and the Mexican War, of those anxious
days leading up to our Civil War, and of the latter momentous
conflict itself, which several times threatened a tragic ending
to the bridge.

Narrow Escapes From Fire

It was stacked for burning, by both the Union
and the Confederate forces, but each time local townsmen succeeded
in dissuading them from their purpose. With the opposing forces
camped on either side of the river, it seems a miracle that the
bridge passed through the war unscathed, when nearly every other
bridge along the river was then destroyed.

But the stoutest works of man are, like himself,
but mortal, and must eventually yield to the ravages of time
and weather. With the old bridge, too, the increased demands
of modern traffic were undoubtedly an accelerating influence
toward the ending of its period of usefulness.

Gradual settlement of one of the arch ribs
had been observed for some 15 years back, induced probably by
a combination of causes, and the floor became noticeably too
weak for modern loads.

A new floor system was installed during the
summer of 1925, which gave temporary relief, but by the following
fall, the continued deformation of the arch ribs had reached
a point considered dangerous, and the bridge was closed toward
the last of November 1925, by the Highway Department, first to
heavy traffic only and shortly afterward to all traffic.

A ferry was installed in December, following,
just above the bridge, operated by local parties which has taken
care of traffic until completion of the new bridge. Several moves
were made during the next few months to secure the repair and
reopening of the old bridge; but after thorough investigation,
it was decided that the large cost involved in attempting the
necessary repairs, with no assurance forthcoming that such repairs
would prove permanent, would not be justified from an economic
standpoint.

Impractical Sentiment

In passing, it should be observed that while
everyone appreciates the historical significance of the old bridge,
and while the strong sentiment evidence looking toward its preservation
as a monument to the past is a worthy one, nevertheless, in the
present day, everything, even sentiment, must sometimes be measured
in terms of dollars and cents; especially where the expenditure
of public funds is involved, and the ever-recurring question
arises: will the ultimate returns on the investment be satisfactory
to the taxpayers, spent along the lines for which they were intended?
The annual cost of maintenance is, also, of course, a vital factor
in arriving at conclusions in such matters.

With the closing of the old bridge, the highway
department engaged in making comparative studies and investigations,
as a result of which a new bridge was unanimously decided upon.
The site selected, downstream or west from the old bridge some
100 feet average distance, also had the merit of eliminating
several very sharp curves in the old road alignment.

Work on plans for the new bridge was started
early in 1926, and completed by June 1st of that year. The securing
of the necessary right of way by Jessamine and Garrard counties
was also initiated in the spring of 1926.

Contracts for the new bridge were sent June
22, 1926, in two parts: one covering the fabrication, erection,
and painting of the 275-foot steel span across the main river
channel; the other including all substructure and concrete work.
The contract for the steel span was awarded to the Mt. Vernon
(Ohio) Bridge Company for $42,821.82, who completed same; but
owing to unforeseen difficulties in securing some of the necessary
right of way, which was not finally obtained until the following
winter, it became necessary to re-advertise the substructure
and concrete work.

On February 22, 1927, the new contract was
awarded to A. M. Cook and Company, of Wartsburg, Tennessee, for
$66, 725.70. A subsequent contract for the fill approach to the
south end of the bridge was awarded September 28, 1927, to Moynahan
and Turner, of Mt. Vernon, Kentucky, for $8,040.

The New Bridge Plans

The plans for the new bridge called for a
total length of 543 feet, including the 275-foot steel span,
with a clearance of 60 feet above extreme low water of the river,
the steel span carrying a seven-inch reinforced concrete road-slab
and curbs. Abutment Six at the south bridge end and Pier Five
are both founded on creosoted pile footings, all other piers
and Abutment O being founded on solid rock.

The deepest footing is at Pier Four, which
extends 21 feet below low-water level of the river, although
Pier Three on the south river edge is practically the same depth.
Pier Four is also the highest pier, the total height above the
footing being 76.4 feet. All piers and abutments are reinforced
throughout, except column footings, some of which are without
steel. Piers Two and Three, which support the steel span, have
circular columns of four feet, eight inches top diameter and
side batter of seven-sixteenths inch per foot; connected with
15-inch web-wall.

The concrete approach spans to steel span
are deck-girders each 53 feet long; two being used at the north
end, where the alignment is straight, and three used at the south
end, where the alignment is a 25-degree curve with transverse
super-elevation on the roadway surface. A new constructive feature
was introduced in these deck-girders, namely that the three beam
stems of each girder were cast first, followed by a later pour
of slab and curbs, the two runs bonded together by use of concrete
keys eight inches by ten inches and two-inch thick. These keys
were spaced at 18 inches centers along the top of each beam stem
at the base of the slab. This method greatly simplifies construction
as compared with the old method of pouring beams and slab monolithic,
as the slab steel does not have to be in place at the time beams
are cast.

All piers and abutments, deck-girder spans
to base of handrail, and road slab across steel span are of Class
A or 1:2:4 mix concrete. The roadway width is 20 feet, except
on the three south approach spans, where standard curve widening
obtains. Roadway wearing surface is to be Kentucky rock asphalt,
two inches thick, which will not be placed, however, until warm
weather allows its successful application.

The handrail on concrete spans is of the rectangular
spindle and baluster type with posts at the ends, quarter and
center points of each span, all of Class D or 1:2:3 mix concrete,
reinforced. The base rail between the posts was cast first, followed
by posts and balusters being cast monolithic over length of span.
Four-inch by six-inch pockets were left in the base rail, into
which spindles were set before casting of balusters, spindle
bases being grouted in afterwards.

Expansion joints of one-inch bituminous felt
are provided where two concrete spans meet, the felt extending
through the handrail; splitting one post, half of which is on
each span. Bronze plates, three-fourth-inch thick, are provided
under expansion ends of deck-girder beams over piers which allow
a free sliding movement. Steel expansion angles are installed
at junction of steel-span with concrete spans on either end.

Plans for the 275-foot steel span include
two full-riveted trusses of the "Pennsylvania" type,
spaced 23 feet apart, with 11 panels of 25 feet each and a maximum
height of 40 feet. Cast steel pedestals are being used at the
end bearings, the north or Pier Two end being fixed; while at
the south or Pier Three, a nest of five, eight-inch diameter
rollers allow expansion.

The floor system consists of transverse 30-inch,
129-pound I-beams at each panel point; longitudinally connected
with five sets of 20-inch, 62-pound I-beam stringers at four
feet, six inch centers across the bridge. The seven-inch concrete
road-slab rests directly on this system.

The total weight of structural steel used
is 601,205 pounds, which includes some 15,000 rivets used; and
also 16 cast iron drain pipes, which are installed through road-slab.
Handrail on steel span consists of two steel six-inch, Z-section
lattices, attached to truss posts.